There’s a reason for the period in the title “Walter Cronkite is Dead.,” says playwright Joe Calarco. Not only does it help convey a news bulletin’s tone of dry finality, but it also punctuates the sense of pessimism that initially inspired Calarco to write the work.

As it happens, “Cronkite” isn’t actually about the late newscaster, once known as “the most trusted man in America.” The humor-laced play, which has its West Coast premiere at San Diego Repertory Theatre this week, is more about the state of civil relations in our politically polarized nation.

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At its center are Margaret (onetime “ER” star and Rep returnee Ellen Crawford) and Patty (the versatile San Diego performer-playwright Melinda Gilb), two women of a certain age who are stuck in an airport during a winter snowstorm. Patty is a loquacious Southern conservative; Margaret is a reserved, progressive Easterner. The play focuses on what happens when mutual preconceptions (theirs, and maybe ours) run up against flesh-and-blood people.

As Calarco explains it, “Cronkite” originated in a much different, much bigger play (ultimately never produced) that was based on survivors’ recollections of the 9/11 attack on the Pentagon.

While he was developing that work, Calarco remembers being surprised by the common ground he felt with people whose politics were very different from his. Around that same time, the playwright also had an eye-opening conversation with his sister.

“We were talking about civil discourse, (how it’s) like two kids throwing sand at each other,” Calarco recalls. “She was very optimistic about, ‘I think it will change.’ I said: ‘I don’t think so. I think we’ve tipped over into a place where civil discourse is dead.’ I said, ‘Walter Cronkite is dead, after all.’

“And the minute I said it, I thought, that’s a great title.”

So taken was Calarco with the idea that he finished the first draft within about five days, basing it on his two favorite characters from the original, ill-fated play.

“I have to say that the title really clarified what the play was about,” as he puts it.

Cronkite, who anchored the “CBS Evening News” from 1962 to 1981 and died in 2009, was a unifying and near-ubiquitous symbol of civility in a time and place before shock jocks and cable-news shoutfests. The sense of the play is that he represented an era when politicians and everyday citizens alike could work out their differences as individuals rather than as presumed enemies.

“It’s certainly about, once you hear someone’s story, it’s hard to demonize them,” says Calarco, a prolific playwright and busy director whose best-known work is “Shakespeare’s R&J,” a Bard adaptation that has played off-Broadway and around the world. (Calarco was last in San Diego three years ago directing a quietly moving production of “The Glass Menagerie” at the Old Globe.)